Drug self-administration in rodents is a useful technique to examine the mechanisms and potential treatment of stimulant abuse. Previous research has shown that stimulant self-administration is greater in rats that are highly active in a novel environment (high responders) compared to rats that are relatively inactive (low responders). In addition, stimulant self-administration is greater in rats raised in an isolated environment compared to rats raised in an enriched environment. The experiments proposed in the present application will determine if rats that are prone to self-administer amphetamine, due to genetic or environmental factors, share a common neural profile of an overactive arousal system. The overall mechanistic framework for the proposed set of experiments is based on the role of the central nucleus of the amygdala (ACe) in regulating arousal due to its extensive cortical and subcortical projections. We hypothesize that the ACe is more active in high responder rats compared to low responder rats and in rats reared in an isolated condition compared to an enriched condition. The effects of ibotenic acid lesions of the ACe on subsequent amphetamine self-administration will be measured. In addition, the amount of c-Fos labeling will be measured in the ACe to determine if the ACe has greater activity in those rats prone to self-administer amphetamine. The findings from these experiments are intended to advance the understanding of vulnerability for stimulant abuse, and will potentially lead to better prevention and treatment interventions.